Novel transthyretin gene mutation in familial amyloid neuropathy in India: Case.

Familial amyloid polyneuropathy (PN), also known as amyloid transthyretin (TTR)-PN is an autosomal dominant adult-onset fatal disease, if not treated. It occurs due to mutations in (TTR) gene which leads to a faulty TTR protein which folds up to form amyloid and gets deposited mainly on nerves and causes length-dependent PN and autonomic dysfunction. We report a case of a 45-year-old female who presented with symptoms of painful peripheral neuropathy for 5 months, a history of deafness for 5 years, and cardiac pacemaker implantation 2 years ago for complete heart block. She denied any symptoms of autonomic dysfunction. Her brother with similar symptoms died of cardiac arrest at the age of 50 years. Clinical examination was suggestive of symmetrical sensorimotor PN. The nerve conduction study was suggestive of axonal sensorimotor PN. Abdominal fat biopsy was negative for amyloid. Sural nerve biopsy was suggestive of amyloid neuropathy. Genetic analysis showed c. 165G > T mutation encoding amino acid p. Lys55Asn on exon-4 of TTR gene. This mutation has not been reported from India.